The present invention relates to the prevention of fraud and more particularly to the prevention of fraudulent misappropriation of credit/debit card authorization numbers and passwords when public pay phones are used.
A fraud scheme that has recently come to the attention of telecommunication service providers involves pay phones located in public areas such as airports, train stations and the like. Due to the nature of those public areas and the great number of installed public phones, most of the pay phones typically have their ringers disabled by the management of those public places. This is to eliminate the often-annoying rings to those phones, which are made, in most instances, by people who have dialed the wrong numbers. Thus, if an unsuspecting person were to pick up one of these pay phones while a call is incoming, he would end up being connected to whoever made the call.
Calling card fraudsters have seized upon these non-ringing pay phones as an opportunity to defraud unsuspecting authorized pay phone users. In particular, what the fraudsters have done is to call pay phones located in public areas, and wait for an unsuspecting authorized pay phone user to pick up the phone to make an outgoing call. There are two ways in which the fraudsters try to trick a user into providing his authorization code and/or pin number via the keypad of the telephone. The first method is where a bogus dial tone and a bong tone are generated from the fraudster""s phone after the pay phone user picks up the handset of the phone. Upon hearing the dial tone and bong tone, the unsuspecting user would dial his 800 access number, calling card number and pin number, and await connection. The connection, of course, never occurs. After a while, the caller simply hangs up, thinking that he must have misdialed, and tries again. The fraudster, in the meantime, has acquired the caller""s authorization code and pin number by receiving the tone associated with the caller""s pressing of the keys of the keypad of the telephone. This generating of a dial tone and bong tone is usually done by means of a tape playback.
A second method whereby an unsuspecting authorized pay phone user is defrauded is when the fraudster uses two lines so that when the authorized user makes a call, he is conferenced by the fraudster via the second line to his destination. In the meantime, the fraudster has captured the authorization number or code of the pay phone user. Once the authorization number has been captured, the fraudster either can let the call be completed or simply hangs up on the authorized user.
There is therefore, a need for a system, and method therefor, of preventing this kind of pay phone credit/debit calling card fraud.
To prevent the type of credit/calling card abuse outlined above; a pay phone of the present invention is provisioned with a circuitry that disables the keypad under certain circumstances. In one embodiment, a sensor circuit is provided for monitoring incoming, or in-bound, calls (from the fraudsters) that are answered by authorized caller, such as for example an airport patron. Thus, with the keypad being disabled, when attempting to dial out, the authorized caller will not hear any tones associated with his pressing of the keys of the keypad. Consequently, the caller would, like most people, naturally flash-hook the phone, thereby disconnecting the incoming call from the fraudster. A clear line of course is then obtained.
To practice the first embodiment, a circuit to be added to the pay phone circuitry monitors any incoming call signals, by way of the incoming ring current. A second circuit is then used to monitor whether the handset of the pay phone has been lifted off-hook. Upon satisfaction of both of those conditions, yet a third circuit will disable the DTMF. (dual tone multi-frequency) encoder of the telephone, so that when pressed, the keys on the keypad would not generate any associated output tones. Attentively, an open circuit may be created to prevent power from being supplied to the keypad if one contact side of the keypad is ordinarily energized.
A second embodiment of the instant invention is to provide a circuit for discriminating the various dial tones to detect a true dial tone, which is 350-440 Hz, provided by the local telephone company or a PBX switch. With the detection of a true dial tone when the handset is lifted off-hook, a clear line is ensured.
Yet a third embodiment of the instant invention provides circuits for monitoring the ring current from incoming calls, whether the handset of the telephone has been lifted off hook, and whether there is a true dial tone. It is only when all three conditions are met that the keypad of the telephone is enabled so that tones associated with the keys pressed by the user on the keypad are generated.
Given that the circuits that are required can be easily added to the conventional telephone circuitry and do not cost a great amount, the present invention is able to prevent the type of fraud practiced by fraudsters mentioned above economically.